This invention relates generally to a margin sensing means for printing machines and more particularly to an electronic margin sensing means for indicating the bottom margin on typewritten sheets. Although there have been a number of significant advances recently in the art of small business machines, the typewriter, with one possible exception, has remained practically unchanged for many years. Numerous gadgetry modifications have been proposed for purposes of commercial exploitation, however, the typewriter regardless of its facade, retains its basic utilitarian form.
Despite substantial interest in the typewriter art over the years, there is one aspect of typewriting that has escaped the designers and builders of these machines. This invention fills a need long felt by typists. That need is the ability to automatically set a bottom margin on the typewritten sheet. Various techniques have been taught by typing instructors to alert the typist that the paper should be changed. These include measuring from the bottom of the paper before insertion, and either marking the paper lightly with a pencil, or pinching the paper to leave a mark. While these methods solve the basic problem for the student or beginner, it becomes a chore or burden on the professional secretary who is often in a hurry, and who may type many pages each day.
This invention provides a fast automatic means for signalling the typist that the bottom margin of the page has been reached and it is not time to change paper. The system is readily adjustable in order that the margin may be changed easily by the typist, thereby conserving time and energy.